Changes in the neuroanatomical organization of the dorsal lateral geniculate nucleus and visual cortex of Macaca monkeys will be studied during development in normal and monocularly deprived animals. The neurons and synapses utilizing GABA, acetylcholine, and other possible neurotransmitters will be identified by means of EM autoradiography, and immunocytochemistry. The effect of monocular deprivation on the distribution and amount of these transmitters will be assessed to test the hypothesis that deprivation is caused by excessive inhibition at one or both of these levels of the visual system.